Sh4mefulDMARC Spoof Detection, Confounders
This page lists known email confounders — legitimate services whose forwarding or inspection behavior disrupts DMARC authentication — organized by owner, network, and IP. Learn more about this data.
Confounder Owners (top 9 by message volume)
| Owner | Networks | Unique IPs | Messages |
|---|---|---|---|
| Amazon | 4 | 34 | 51,197 |
| Microsoft | 3 | 4,445 | 27,583 |
| 1 | 1 | 1,265 | |
| Proofpoint | 4 | 115 | 665 |
| Mimecast | 4 | 31 | 448 |
| Cisco | 2 | 22 | 218 |
| Intermedia | 1 | 1 | 73 |
| Barracuda | 1 | 30 | 70 |
| OpenText | 1 | 4 | 36 |
Confounder Networks
Top 28 by failure volume| Network | Owner | Unique IPs | Messages |
|---|---|---|---|
| AT-88-Z ⚠ | Amazon | 26 | 47,737 |
| UK-MICROSOFT-20060601 ⚠ | Microsoft | 1,017 | 14,115 |
| MSFT ⚠ | Microsoft | 3,373 | 13,390 |
| AMAZON-2011L ⚠ | Amazon | 1 | 2,408 |
| GOOGLE ⚠ | 1 | 1,265 | |
| AMAZO-4 ⚠ | Amazon | 6 | 971 |
| PROOFPOINT-NET-NORTH-AMERICA ⚠ | Proofpoint | 83 | 501 |
| MNA-95 ⚠ | Mimecast | 26 | 320 |
| CISL-7 ⚠ | Cisco | 14 | 186 |
| EONIX ⚠ | Eonix/Scamalytics | 1 | 128 |
| PROOF ⚠ | Proofpoint | 27 | 118 |
| AMAZON ⚠ | Amazon | 1 | 81 |
| MICROSOFT-IPV6-BLK ⚠ | Microsoft | 55 | 78 |
| INTRMD-1 ⚠ | Intermedia | 1 | 73 |
| BARRA-7 ⚠ | Barracuda | 30 | 70 |
| MIMECAST-NET2 ⚠ | Mimecast | 1 | 67 |
| MIMECAST-NET ⚠ | Mimecast | 2 | 58 |
| ZIXCORP ⚠ | OpenText | 4 | 36 |
| IRONPORT-DH ⚠ | Cisco | 8 | 32 |
| NAVI-207-211 ⚠ | 5 | 25 | |
| UK-PROOFPOINT-20151223 ⚠ | Proofpoint | 3 | 24 |
| PAUBOX-01 ⚠ | 8 | 23 | |
| pfptnl ⚠ | Proofpoint | 2 | 22 |
| RN-52 ⚠ | 14 | 22 | |
| UK-MIMECAST-NET3 ⚠ | 3 | 9 | |
| UK-MIMECAST-NET1 ⚠ | 2 | 6 | |
| MIMECAST-AU ⚠ | Mimecast | 2 | 3 |
| UK-MIMECAST-NET2 ⚠ | 1 | 2 |